I have a FrigiKing Tappan Model PHR48 heat pump in our home which is about 34 years old and was maintained by the previous owners over the years with various components replaced to keep it functioning. We hardly ever use it for cooling as the climate is fairly mild on the Central Coast of California and our home is fairly shaded with trees. We have a pellet stove which we use for most of our heating requirements in the winter time. The compressor and reversing valve on the unit are functioning. It has an auto change over thermostat controlling it in the home with the wires R, Y, G, O, W2. It appears the thermostat provides for two stages for the heating and the cooling with double mercury switches on the heating and cooling temperature setting arms. I understand the function of W2 is to activate the 10KW electric heater strip as the second stage in heating to help with the compressor when there is a high heat demand. On the thermostat there is also a emergency heat slide switch which when switched on appears to shut off the compressor and keep the air circulation fan running but doesn't produce any heat from the unit. Because there is no wire running to the "E" terminal on the thermostat, I am assuming that the thermostat had come with the feature but the heat pump didn't offer both an auxilary heat and an emergency heat function so they didn't wire that feature on the thermostat. While the compressor is functioning and doesn't make any strange noises, it doesn't produce much heat or cool anymore. I had an HVAC guy come out and put a set of gauges on the unit and he said the R22 charge is low and the defrost clock is not functioning so my auxilary heat strips are not coming on. He said the unit is so old that he couldn't work on it and wanted to sell me a new unit. I don't have the money for a new unit and since I really don't use the compressor for cooling, I would like to just utilize the electric heater strips occasionally in the winter time. I asked the technician if we could move the W2 wire over to the "E" terminal and just use those heater strips for occasional use until we can afford to buy a new unit. He didn't know. Would anybody else out there have an answer.

Yes, if you move the Aux W2 to E then the heat strips should only be active when you call for emergency heat. As long as you know you have to manually call for heat and then stop the call at the thermostat you will be fine.

Thanks for the response Freon. When you say "you have to manually call for heat" does that mean when the emergency heat switch is in the "on" position that the mercury switches on the thermostat are bypassed and that the heater strips are on continuously without regard to the temperature set on the thermostat. One other question, if the defrost clock is not functioning as the tech claimed will putting the W2 wire onto the "E" terminal of the thermostat be bypassing the clock so I don't have to worry about it being defective.

Check how your thermostat handles emergency heat. Usually it is set to be the only heat source controlled by the thermostat. Aux heat works in parallel with the heat pump based on how much colder the house os than the set temperature.

Check with the thermostat. Usually the Emergency is independent of the condenser. However there may still be power to the condenser control board and it may try and function but should not affect your using emergency heat.